syncthing/lib/connections/registry/registry.go
greatroar 7c292cc812
lib/connections: Fix and optimize registry (#7996)
Registry.Get used a full sort to get the minimum of a list, and the sort
was broken because util.AddressUnspecifiedLess assumed it could find out
whether an address is IPv4 or IPv6 from its Network method. However,
net.(TCP|UDP)Addr.Network always returns "tcp"/"udp".
2021-10-06 10:52:51 +02:00

100 lines
2.5 KiB
Go

// Copyright (C) 2019 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.
// Registry tracks connections/addresses on which we are listening on, to allow us to pick a connection/address that
// has a NAT port mapping. This also makes our outgoing port stable and same as incoming port which should allow
// better probability of punching through.
package registry
import (
"strings"
"github.com/syncthing/syncthing/lib/sync"
)
var (
Default = New()
)
type Registry struct {
mut sync.Mutex
available map[string][]interface{}
}
func New() *Registry {
return &Registry{
mut: sync.NewMutex(),
available: make(map[string][]interface{}),
}
}
func (r *Registry) Register(scheme string, item interface{}) {
r.mut.Lock()
defer r.mut.Unlock()
r.available[scheme] = append(r.available[scheme], item)
}
func (r *Registry) Unregister(scheme string, item interface{}) {
r.mut.Lock()
defer r.mut.Unlock()
candidates := r.available[scheme]
for i, existingItem := range candidates {
if existingItem == item {
candidates[i] = candidates[len(candidates)-1]
candidates[len(candidates)-1] = nil
r.available[scheme] = candidates[:len(candidates)-1]
break
}
}
}
// Get returns an item for a schema compatible with the given scheme.
// If any item satisfies preferred, that has precedence over other items.
func (r *Registry) Get(scheme string, preferred func(interface{}) bool) interface{} {
r.mut.Lock()
defer r.mut.Unlock()
var (
best interface{}
bestPref bool
bestScheme string
)
for availableScheme, items := range r.available {
// quic:// should be considered ok for both quic4:// and quic6://
if !strings.HasPrefix(scheme, availableScheme) {
continue
}
for _, item := range items {
better := best == nil
pref := preferred(item)
if !better {
// In case of a tie, prefer "quic" to "quic[46]" etc.
better = pref &&
(!bestPref || len(availableScheme) < len(bestScheme))
}
if !better {
continue
}
best, bestPref, bestScheme = item, pref, availableScheme
}
}
return best
}
func Register(scheme string, item interface{}) {
Default.Register(scheme, item)
}
func Unregister(scheme string, item interface{}) {
Default.Unregister(scheme, item)
}
func Get(scheme string, preferred func(interface{}) bool) interface{} {
return Default.Get(scheme, preferred)
}